<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>   
    .item-class{        margin:5px 0;        border-bottom:1px solid #999;    } 
    #addBtn{        margin-bottom: 10px;    }   
    </style>
</head>
<body>
  <h1>Fetch Extensions</h1>
  <script src="./popup.js"></script>
</body>
</html>